A variety of automatic focussing and automatic aperture setting cameras are known which energizes a flash lamp to provide a first generally low intensity flash of light initiated as the shutter release button is depressed. The flash light is reflected from the object to be photographed and detected by a photosensing means which provides a signal indicative of the range to the object to be photographed. This range signal has been used to adjust the position of the focussing leans, and it has been proposed to automatically set the lens aperture in response to this range signal for a flash picture at the range involved if flash operation was selected. The flash lamp is then again automatically energized to provide a high intensity flash of light as the shutter opens in response to the same shutter release button depression which produced the range determining flash of light.
As disclosed in the applicant's U.S. Pat. No. 4,473,285 issued Sept. 25, 1984, which fully discloses only the lens focussing portion of such a camera, the range signal is applied to individual signal level detectors which are set to be triggered by range signals which exceed different levels of progressively decreasing magnitude representing the limits of contiguous range zones starting with the closest range zone and ending with the next farthest range zone. Three such zones are utilized in the camera disclosed in this application, making a total of four range zones overall. Accordingly, a signal generated by a range light pulse reflected from an object in the nearest range zone will actuate all of the level detectors involved and signal generated by a light pulse reflected from an object at a range within the furthest range zone will not operate any of the level detectors. Focussing means respond to the absence of any triggered signal level detector by focussing the camera in the farthest range zone and responds to the triggered signal level detector associated with the nearest range zone to focus the camera for that range zone.
While the focussing system just described is very satisfactory for a limited number of range zones where a few signal level detectors and associated focus control circuitry are utilized, this approach becomes uneconomic where a large number of range zones are utilized, and particularly where the range zone signals are also utilized for automatic lens aperture control during flash operation. As is well known for flash operation the lens speed is fixed and different lens apertures or "f-stops" are selected depending on the camera to object distance. If lens aperture selection is determined by utilizing an "f-stop" value zone approach like the focussing zone system just described, an additional group of signal level detectors and associated aperture control circuitry is required since there would normally be different range transition zones for focussing and lens control. Where a large number of range and aperture control zones are involved, as required for best picture taking results, the expense of the signal level detector and associated circuitry makes a signal level detector system as described undesirable from an economic standpoint.